UNIVERSITY OF FLORIDA IFAS
Ft. Lauderdale ARC Research Report FL-76-3
Phytotoxicity Response of Environmental Plants to Pesticides
James A. Reinert and P. L. Neel
University of Florida, IFAS
ARC, Ft. Lauderdale, Fla. HUN LIBRARY
December 28, 1976
AUG 14 1978
I.F.A.S.- Univ. of Florida
Pesticides* are used frequently in nurseries for the production oT
quality environmental (ornamental) plants and-by home-owners-to protect
their landscape plantings from numerous phytophagous mites and insects.
Oil emulsions are often added to insecticides and miticides to enhance
their effectiveness, however there is little data on the phytotoxicity of
these combinations on environmental plants. These studies were made in an
effort to gain phytotoxicity information on environmental-plant species
commonly grown in-south Florida.---In the following 3-experiments, insec---
ticides, miticides, FC-435 citrus spray oil-,-and 2 of these insecticides
each in combination with FC-435 oil were evaluated. Similar phytotoxicity
evaluations with other insecticides;:-but no insecticide in combination
with oil emulsions, have been done and have.proven to-be very useful to
the ornamentals industry, home-owners, and pesticide producers. Plants
used in these tests are listed in Tables 2, 4, and 5.
*Mention of a trademark name or a proprietary product does not constitute a
guarantee or warranty of the product by the University of Florida and does
not imply its approval to the exclusion of other products that may also be
Materials and Methods
Phytotoxicity studies on 24 species of environmental plants were
conducted with 12 miticides at the Agricultural Research Center, Ft.
Lauderdale, FL. Tests were conducted during October and November, 1975,
under 57% shade in a wood lath house on well established, rapidly growing
plants in gallon-size black plastic containers. -Plants were grown in a
sand-peat-muck nursery soil mix (1:2:1 by volume), and were fertilized
with a tablespoon of 18-6-12 OsmocoteR plus a teaspoon of Tri-NiteR
secondary plant food before the test was started and did not require ad-
ditional fertilizer during-the test period. Irrigation was supplied, as
needed, by overhead sprinklers. Table 1 gives the miticides and the do-
sages of each that were evaluated.
Table 1. Miticides, formulations and rates of active ingredient per
100 gal of water used in phytotoxicity evaluations.
AI/100 Gal (lb)
Miticides IXz 2XY
AcarabenR 4EC 0.5 1
CGA-12223 10G l.o. o 10x 20x
Di-SystonR 6EC 0.5 1
FuradanR 10G 10x 20x
KelthaneR 18.5%EC 0.5 1
MorestanR 25WP_ 0.25 0.5
Omite" 30WP 1 2
Pentac^ 50WP 0.5 1
PlictranR 50WP 0.25 0.5
SystoxR 6EC 0.4 0.8
TedionR 50WP 0.25 0.5
TemikR 10G 10x 20x
zlX = lbs. active ingredient at manufacturers recommended rate.
Y2X = ibs. active ingredient at twice recommended rate.
XGranular materials applied at given lbs. active ingredient/acre.
**Data previously published as: Reinert, J. A., and P. L. Neel. 1976.
Phytotoxicity of miticides on selected environmental plants. Proc. South,
Nurs. Assoc. Res. Conf. 21:44-7.
Plants in this experiment were arranged into 3 identical blocks of
25 rows each containing 24 plant species. One row of each 3 blocks served
as an untreated check row; the other 24 rows were used for treatments with
the low and high rates of each of the 12 chemicals. This provided plants of
each species for treatment at each rate on 3 different dates: October 27,
November 3, and November 10. Dry foliage was sprayed to the point of run-off
on each date using a 2-gal compressed air sprayer. Plywood shields were used
between plants of different treatments to prevent drift. Plants were watered
sufficiently prir -to the.treatments so-as to allow 24 hours between treatments-
and the next-irrigation.- Phytotoxicity evaluations were made 3 days after-each
application and 16 days-after the November 10-application. Plant damage was----
rated on a 0-5 scale, with_0 representing no apparent damage and 5 very severe
damage. Notes of-the types of-damage observed were also made. Types of foliage
injury symptoms included, tip (T), blade (B), or marginal burn (M); yellowing
and/or mottling-(chlorosis) (C); cupping-and/or leaf deformation -(wrinkling or
distortion of the petiole-or blade) (D).
Results and Discussion
The relative amount and type of injury observed on November 26 on each
plant species are shown in-Table-2. Araucaria, Asparagus, Carissa, Chrysalido-
carpus, Coccoloba, Dizygotheca,-Murraya, and Veitchia were the only species ---
which did not exhibit noticeable injury symptoms to any of the miticides.-
Brassaia, Buscida, Ficus retusa, Jasminum, and Ligustrum were the most sensitive
plants. Chlorobenzilate appeared to cause the most damage to the largest number
(9) of species of any of the 12 chemicals tested. In general the granular for-
mulations of CGA-12223, carbofuran and aldicarb appeared to the the least likely
to cause injury over the widest range of plant materials. Aldicarb did not in-
jure any of the test species.
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Because plants in this test were growing vigorously and were under
partial shade, they were in a very tender state of growth and the damage
reported herein would probably be excessive if compared to less succulent
plants growing in full sun. Hence it would be unlikely for an applicator
to obtain any more damage with these miticides on these species than was
obtained in this test.
Materials and Methods
Treatments were conducted under 57% wood lath shading on actively.
growing plants established in 6-inch diam black plastic containers.
Plants were grown in a sand-peat-muck nursery soil mix -(-12:1 by volume)
and were fertilized with 0.7 oz of 18-6-12 Osmocote slow-release ferti-
lizer/pot at the start of the experiment. Water was supplied as needed
by overhead sprinklers.
Malathion, ethion, and combinations of each with FC-435 citrus spray
oil, as shown in Table-3, were applied to the plants by foliar spray-with---.
a 2-gal compressed CO2 sprayer (ca 40 psi). Two applications of each for-
mulation were made 4 weeks apart and plants were sprayed to the point of
run-off. Treatments were applied May 25 and June 22, 1976. The temperatures--
on the days of application were between 85 and 900F.
All plants were arranged into 4 identical blocks of 11 rows each con-
taining 28 plant species. Two rows of each block served as untreated checks
with the other 10 rows each receiving 1 of the treatments, therefore, 4 plants
of each species were sprayed with each treatment. Plywood shields were used
between each row during spraying to minimize drift between treatments.
***Data previously published as: Reinert, J. A., and P. L. Neel. 1976.
Evaluation of phytotoxicity of malathion, ethion, and combinations of
FC-435 spray oil with each on twenty-eight species of environmental
plants under slat shade. Proc. Fla. State Hortic. Soc. 89: (in press).
Table 3. Insecticides, formulations, and rates of active ingredient
per 100 gal of water used in phytotoxicity evaluations.
Insecticide (lb) (%)
a Malathion 57%EC 1.25
b Malathion 57%EC + FC-435 oil 1.25 0.5
c Malathion 57%EC + FC-435 oil 1.25 0.7
d Malathion 57%EC + FC-435 oil 1.25 1.0
e FC-435 oil 1.0
f FC-435 oil 1.3
g Ethion 4EC 0.25 -
h Ethion 4EC 0.37 -
i Ethion + FC-435 oil 0.47ECz 0.37 0.5
j Ethion + FC-435 oil 0.625ECz 0.37 0.7
ZTreatments consisted of formulated mixtures.------
Plant damage was rated on a 0-5 scale, with 0 representing no appar-
ent damage and 5 very severe damage. Notes on the type of damage obser-
ved were also made. Types of foliar injury symptoms included burning of
the tip (T), blade (B), or margin (M): blade yellowing and/or mottling
chlorosiss) (C); cupping or deformation of the blade (D); and spotting or
oil-soaking-of-the blade (S).- Leaf fall (F) would typically follow-
chlorosis symptoms*-in a number-of plants. : Iansome cases the shoot apex
was killed (A).
Results and Discussion
The amount and type of injury to each plant species are shown in
Table 4. Certain plants were quite sensitive to -all treatments whereas
others were very tolerant. Ethion was much safer than malathion on a
wider range of species at the rates used. Most oil and oil-insecticide
combinations caused greater injury than application of insecticide alone.
As the oil concentration was increased usually the amount of-damage was
increased. The most severe damage, both in degree and numbers of plant
species injured was caused by the malathion plus 0.7 and 1% oil emulsions.
Table 4. Phytotoxicityz evaluations of 10 pesticide rates or combinations
applied to foliage of 28 environmental plants.
Insecticides or Combinations from Table 1
Plant species a b c d e f g h i j
2.5B 3D,M 3D,M
M,T T T
2.5C 2.5C 3C,T
M,T,F M,T,F F
IC,T 2C,F 2.5C
0 IS 1.5B
0 0 0
0 0 0
0 0 3S
0 IB IC,S
0 0 0
0 0 0
0 0 2.5B
0 0 2C,T
1.5B 2B,D 3B,D
1.5B 1.5C 0
0 O' lID
0.5S 0.5S 2C,F 2C,F 2.5B
2C,F 2C,F 0 0 2C
IS iS IS IC,F 2.5C
0 0 0 0 0
3 observed phyto.,
svere damage, 5 =
,formation of new
very slight damage, 2
= slight damage, 3 = moderage damage,
. = Marginal burn, B = Blade burn, T = Tip burn, C = Chlorosis,
leaves, F = Falling leaves, S =Spotting or oil soaking of leaves.
Under the conditions of these tests, the following plants were
sensitive to most treatments: Bischofia javanica, Bucida bucerus,
Ficus retusa, Hibiscus spp., and Psidium guajava. Most treated
plant species showed no injury at all.
Several of the plants including Caryota maxima, Coccoloba uvifera,
Ficus spp., Hibiscus rosa-sinensis, Ligustrum japonicum, Livistona
chinensis, and Murraya paniculata exhibited leaf spotting and/or oil
soaked spots as-a result-of the oil emulsions. The spotting abnormali-
ties had almost completely disappeared by 4-weeks following the final -
spray treatments when the final evaluations were made. This may have
been due to absorption of the oil and/or to continued expansion of the
leaves. Even L. chinensis, the most severely damaged species appeared
normal by this time.
On many plants the damage was most visible at the time of the 3-day
evaluation.-Thus,-even though-the final observation may-not have indi-.
cated much damageg,-the-phytotoxicity rating-in-Table 4 tends to reflect
the 3 day damage levels. In addition,-it:should be-stressed that these
tests were conducted under partial shade. Therefore, effects of these
treatments in full sun might not be directly comparable to results re---
ported here. Higher leaf-temperatures-in full sun might have resulted
in even more oil-induced phytotoxicity than we observed.
Materials and Methods
In test 3, 46 species of environmental plants (listed in Table 5)
were evaluated for phytotoxicity due to repeated applications of acephate
(OrtheneR). Plants were grown and treated under conditions the same
as those enumerated for Experiment 2.
The plants were arranged into 4 identical blocks of 3 rows each
containing 46 plant species. One row of each block served as an un-
treated check, another row was treated with acephate at 0.5 lb AI/100
gal water, while the third row was treated with acephate at a rate of
1.0 lb AI/100 gal water. Therefore, 4 plants of each species were
sprayed with each treatment. Four applications of each rate were made
at weekly intervals with a 2-gal compressed air sprayer (ca 40 psi).
Plants were sprayed to the point of run-off. Sprays were applied on
September 7, 14, 21, and 28, 1976. Plants were examined within 3 days
following each application and at 6 weeks following the final treatment.
Results and Discussion
Of the 46 plant-species evaluated (Table 5) no plants were actually -
damaged by-a total of 4 applications of acephate; neither were any damaged----
chronically, i.e., no chemically induced distortions in new growth were ob-
served 6 weeks after the-final spray treatment. However, there was some dis-
tortion observed; apparently it was induced by mites which were not killed by
the repeated treatments with acephate. Upon close examination of these dis-
torted plants, high populations of Polyphagotarsonemus latus, a tarsonemid
mite, and Brevipalpus phoenicis, a tenuipalpid mite, were observed. This
apparently selective activity of acephate on mites could pose a problem in
situations where acephate might be used exclusively; resistant mites could
build up to damaging levels quickly and cause severe plant damage. Appar-
ently a predatory mite or other predator was eliminated by the acephate
treatments, thus allowing the 2 species of mites to develop unhampered.
In comparison, only very low, non-damaging populations of these mites
were observed on the untreated check plants.
Table 5. Environmental plants evaluated for phytotoxicity of acephate at
0.5 and 1.0 lb AI/100 gal.
Asparagus densiflorus 'Sprengeri'
Buxus microphylla-Var. japonica -
Carissa grandiflora- __
Caryota maxima = C. rumphiana
Codiaeum variegatum Var. Pictum 'Brav,
Eugenia uniflora ~-
Ficus retus (F.- nitida-is a synonym)
Hibiscus calycinus = calyphyllus
Ixora coccinea 'Super King'
--Livistona chinensis -.
o' Pittosporum tobira 'Wheeleri'